[89] This _vivarium_ is a triangular piece of ground, the wide end of which touches the wall of the Amphitheatrum Castrense; the narrow end is only just wide enough for the body of a man to pass through an aperture made in it, as the ground is between a wall of Aurelian on the inner side, and a wall of the Sessorium on the outer side, preserved by Aurelian as an outwork. This was the scene of the celebrated ambuscade of Belisarius, by means of which the Goths were driven away from Rome, as described by Procopius (De Bello Gothico, lib. i. c. 22.) [90] PRO S. IMP. M. ANTONI . GORDIANI . PII FELICIS AVG. ET TRANQVILLINAE SABI NAE AVG. VENATORES IMMVN. CVM CV STODE VIVARI PONT. VERVS MIL. COH VI. PR. CAMPANIVS VERAX. MIL. COH. VI PR. FVSCIVS CRESCENTIO ORD CVSTOS VIVARI. COHH. PRAETT. ET VRBB DIANAE AVG. D. S. EX. V. P. DEDICATA XII. KAL. NOV. IMP. D. N. GORDIANO AVG. ET POMPEIANO COS. (Inscription found in Rome in 1710, and printed by Nibby, Roma Antica, vol. i. p. 386.) [91] A compartment of this is shewn in one of the _graffiti_, found in the excavations of 1874. [92] “Caius princeps in circo pegma duxit.” (Plinii Nat. Hist., xxxiii. 16.) [93] “Ludiviæ sunt, quæ ad voluptatem oculorum atque aurium tendunt. His annumeres licet machinatores, qui pegmata per se surgentia excogitant, et tabulata tacite in sublime crescentia, et alias ex inopinato varietates, aut dehiscendentibus quæ cohærebant, aut his quæ distabant, sua sponte coeuntibus aut his quæ eminebant paulatim in se residentibus.” (Seneca, Epist., 88, s. 19.) [94] “Sic pugnas Cilicis laudabat, et ictus; Et pegma et pueros inde ad velaria raptos.” (Juvenal, Satyr iv. 121, 122.) [95] See p. 49. [96] Photos., No. 3283. [97] Photos., No. 3286, and Plate VII. [98] Photos., No. 3263. [99] Those English people who remember Sadler’s Wells Theatre in London about 1820, must know that there was always a sheet of water or reservoir under the stage, and trap-doors in the floor by which sea-monsters could be introduced. The amusements of the old Roman people seem to have been frequently of this kind. Naval fights in boats might have been performed in the Colosseum, and a great deal of machinery must have been required to remove the floor and replace it. A wooden Roman bridge still remains under water near Compiègne in France, of which M. Peigné Delacourt has published an account, with engravings of it, so that wood under water is preserved in the same manner as when it is buried in a wet soil. This is well known in the case of piles for bridges, and in those under the city of Amsterdam. [100] See Plate XXVI.